High-frequency switch module and high-frequency switch apparatus

ABSTRACT

A high-frequency switch module includes a multi-layer substrate, and a switch circuit mounted on the multi-layer substrate. The multi-layer substrate includes a terminal through which a plurality of high-frequency signals in a plurality of frequency bands are input and output, a plurality of switch terminals, terminals to which control signals to control the switch circuit are supplied, current paths that connect the terminals to the switch circuit, and resistors that are provided on the current paths and have resistance values greater than the resistance values of the current paths. The switch circuit connects the terminal to the switch terminals corresponding to the frequency bands of high-frequency signals input and output through the terminal based on the control signals.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to high-frequency switch modules andhigh-frequency switch apparatuses, and more particularly, tohigh-frequency switch modules and high-frequency switch apparatuses usedin wireless communication apparatuses which can be used in a pluralityof different communications systems.

2. Description of the Related Art

Examples of mobile communications systems include GSM 900 (Global Systemfor Mobile Communications 900), GSM 1800 (Global System for MobileCommunications 1800) widely used in Europe, GSM 850 (Global System forMobile Communications 850) widely used in North America, and PDC(Personal Digital Cellular) system widely used in Japan. Examples ofCDMA systems used in parallel with GSM include CDMAOne (Code DivisionMultiple Access One) and IMT-2000 (International MobileTelecommunications 200). Recent widespread use of mobile phones hascaused a problem in that frequency bands assigned to each of the mobilecommunications systems are not sufficient for providing services to allof the users of the systems, resulting in interruptions ofcommunications or difficulties in making connections particularly inlarge city areas. Thus, it has been proposed to allow a user to use aplurality of mobile communications systems thereby substantiallyincreasing the available frequencies, improving service, and enablingefficient use of infrastructures.

Accordingly, an antenna switch circuit disclosed in Japanese UnexaminedPatent Application Publication No. 2004-253953 has been disclosed. Theantenna switch circuit includes an antenna and a switch circuit. Theantenna transmits and receives transmission and reception signals in aplurality of frequency bands. The switch circuit switches transfer pathsso as to correctly output the reception signals in a plurality offrequency bands input from the antenna to the corresponding receivercircuits, as well as switches the transfer paths so as to correctlyoutput the transmission signals to the antenna. Such a switch circuitincludes a plurality of FET transistors, and the FET transistors, whichare switched ON or OFF by control signals, switch transfer paths. Theabove-described antenna switch circuit enables transmission andreception signals in a plurality of types of frequency band to behandled in mobile phones.

In such an antenna switch circuit, it is necessary to prevent noisegenerated in a printed circuit substrate on which the antenna switchcircuit is mounted from being input to the switch circuit of the antennaswitch circuit. Accordingly, a capacitor, one end of which is grounded,is connected to the path through which a signal for controlling theswitch circuit is transferred. This enables the noise generated in theprinted circuit substrate to be transferred to the ground through thecapacitor via a ground electrode within the printed circuit substrate,whereby the noise is prevented from being input to the switch circuit.

However, the above described antenna switch circuit still has a problemin that the high-frequency characteristics of the switch circuit aredeteriorated due to noise, as will be described below. FIG. 5 is across-sectional view of an antenna switch circuit 100 and a printedcircuit substrate 102 on which the antenna switch circuit 100 ismounted. The printed circuit substrate 102 includes the antenna switchcircuit 100 and a capacitor 104 mounted thereon. The capacitor 104 isgrounded through a ground electrode 106 provided within the printedcircuit substrate 102 (it is not illustrated how the ground electrode106 is grounded). The antenna switch circuit 100 is also groundedthrough the ground electrode 106.

In the antenna switch circuit 100, noise is also generated in the switchcircuit (not illustrated) of the antenna switch circuit 100, in additionto the noise generated in the printed circuit substrate 102. These kindsof noise are transferred to the ground side through the capacitor 104and the ground electrode 106 within the printed circuit substrate 102.However, as illustrated by an arrow in FIG. 5, a portion of the noise isinput to the antenna switch circuit 100 through the ground electrode 106when the antenna switch circuit 100 is connected to the ground electrode106. Due to this, the noise is also input to the switch circuit of theantenna switch circuit 100, whereby a transmission signal is modulatedby the noise. As a result, the harmonics of the transmission signal aredistorted and thereby the high-frequency characteristics of the switchcircuit are deteriorated.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of thepresent invention provide a high-frequency switch apparatus and ahigh-frequency switch module in which noise is prevented from beinginput to a switch circuit through a capacitor.

A high-frequency switch module according to a preferred embodiment ofthe present invention preferably includes a first substrate and a switchcircuit mounted on the first substrate. The first substrate preferablyincludes a common terminal through which a plurality of high-frequencysignals in a plurality of frequency bands are input and output, aplurality of switch terminals, a control terminal to which a controlsignal to control the switch circuit in accordance with frequency bandof a high-frequency signal input or output through the common terminalis applied, a current path that connects the control terminal to theswitch circuit, and a resistance portion arranged to reduce noisepassing through the current path, the resistance portion preferablybeing provided in series in the current path and having a resistancevalue greater than a resistance value of the current path. The switchcircuit preferably connects the common terminal to the switch terminalbased on the control signal.

A high-frequency switch apparatus according to another preferredembodiment of the present invention preferably includes a firstsubstrate, a second substrate on which the first substrate is mounted,and a switch circuit mounted on the first substrate. The first substratepreferably includes a common terminal through which a plurality ofhigh-frequency signals in a plurality of frequency bands are input andoutput, a plurality of switch terminals, a control terminal to which acontrol signal to control the switch circuit in accordance with thefrequency band of a high-frequency signal input or output through thecommon terminal is applied. The switch circuit connects the commonterminal to the switch terminal based on the control signal. The secondsubstrate preferably includes a current path including one end which isconnected to the control terminal, and a resistance portion arranged toreduce noise passing through the current path, the resistance portionpreferably being provided in series in the current path and having aresistance value greater than a resistance value of the current path.

According to preferred embodiments of the present invention, noise isprevented from being input to a switch circuit through a capacitor.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a high-frequency switch apparatus includinga high-frequency switch module according to a preferred embodiment ofthe present invention.

FIG. 2A illustrates the back surface of a multilayer substrate, and FIG.2B illustrates the front surface of the multi-layer substrate.

FIG. 3A is a graph illustrating the experiment results of a firstexemplary experiment, FIG. 3B is a graph illustrating the experimentresults of a second exemplary experiment, and FIG. 3C is a graphillustrating the experiment results of a third exemplary experiment.

FIG. 4 is a block diagram of a high-frequency switch apparatus accordingto another preferred embodiment of the present invention.

FIG. 5 is a cross-sectional structure diagram of a known antenna switchcircuit and a printed circuit substrate on which the antenna switchcircuit is mounted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a high-frequency switch module and a high-frequency switchapparatus according to preferred embodiments of the present inventionare described.

Hereinafter, a high-frequency switch module according to a firstpreferred embodiment of the present invention is described withreference to the drawings. FIG. 1 is a block diagram of a high-frequencyswitch apparatus 70 including a high-frequency switch module 10. Thehigh-frequency switch apparatus 70 is preferably used in mobile phonesthat can handle transmission and reception signals in a plurality oftypes of frequency band, for example. The high-frequency switchapparatus 70 switches transfer paths so as to correctly output thereception signals in a plurality of frequency bands input from theantenna to the corresponding receiver circuits, and switches thetransfer paths so as to correctly output the transmission signals to theantenna.

The high-frequency switch apparatus 70 is preferably configured bymounting the high-frequency switch module 10 on a printed circuitsubstrate 50, as illustrated in FIG. 1. The printed circuit substrate 50preferably includes an antenna 30 and capacitors C1 to C3 providedthereon. The high-frequency switch module 10 preferably includes amulti-layer substrate 12, a switch circuit 14, SAW filters 20, 22, 24,26, and 28, resistors R1 to R3, and current paths S1 to S3. Note thatthe resistors R1 to R3 are respectively connected in series to thecurrent paths S1 to S3, and the SAW filters 20, 22, 24, 26, and 28include balanced output terminals.

The multi-layer substrate 12 is preferably a substrate having a circuitprovided therein. FIG. 2A illustrates the back surface of themulti-layer substrate 12, and FIG. 2B illustrates the front surface ofthe multi-layer substrate 12. The back surface of the multi-layersubstrate 12 is a surface that faces the printed circuit substrate 50when the multi-layer substrate 12 is mounted on the printed circuitsubstrate 50. The front surface of the multi-layer substrate 12 is asurface that is parallel with the back surface of the multi-layersubstrate 12.

As illustrated in FIG. 2A, the back surface of the multi-layer substrate12 preferably includes terminals T1 to T28 provided thereon. Asillustrated in FIG. 1, the terminals T1 and T2 are transmittingterminals to which transmission signals GSM-Tx1 and GSM-Tx2 of a GSMsystem are respectively input from transmitter circuits (notillustrated). The terminals T3 to T12 are receiving terminals from whichreception signals Rx1 to Rx5 of a GSM system are respectively output toreceiver circuits (not illustrated). The terminals T13 to T15 arecontrol terminals to which are applied control signals Vc1 to Vc3 tocontrol operation of the switch circuit 14 in accordance with thefrequency bands of high-frequency signals input and output through theantenna 30. The terminal T16 is a power terminal to which a power supplyvoltage Vdd to drive the switch circuit 14 is applied. The terminals T17to T25 are grounded through a GND terminal (not illustrated). Theterminal T26, to which the antenna 30 is connected, is a common terminalthrough which high-frequency signals in a plurality of frequency bandsare input and output. The terminals T27 and T28 in FIG. 2 A may begrounded through a GND terminal on the printed circuit substrate 50. Theterminals T27 and T28, which have areas greater than those of theterminals T1 to T26, are fixed to electrodes (not illustrated) on theprinted circuit substrate 50 side, thereby fixing the printed circuitsubstrate 50 and the multi-layer substrate 12 in FIG. 1 together.

As illustrated in FIG. 2B, the front surface of the multi-layersubstrate 12 preferably includes the switch circuit including asemiconductor such as CMOS, the SAW filters (surface acoustic wavefilters) 20, 22, 24, 26, and 28, the resistors R1 to R3, and inductorsL1 to L5 mounted thereon. The switch circuit 14, the SAW filters 20, 22,24, 26, and 28, the resistors R1 to R3, and the inductors L1 to L5 areelectrically connected respectively to the terminals T1 to T26illustrated in FIG. 2A through via hole conductors and wiring providedwithin the multi-layer substrate 12. Hereinafter, more details aredescribed with reference to FIGS. 2A and 2B. Note that, preferably, theSAW filters 20 and 22 are combined and housed in a single package, andthe SAW filters 24 and 26 are combined and housed in a single package.The SAW filters 20, 22, 24, 26, and 28 are filters having abalanced-unbalanced conversion function.

The circles illustrated in FIG. 2B are via hole conductors provided onthe uppermost layer of the multi-layer substrate 12. The uppermost layerof the multi-layer substrate 12 includes via hole conductors b1 to b39provided thereon. The terminals T1 and T2 are electrically connected tothe switch circuit 14 respectively through the via hole conductors b1and b2.

The terminals T3 and T4 are connected to the SAW filter 20 respectivelythrough the via hole conductors b3 and b4. Further, the via holeconductors b3 and b4 are connected to the balanced terminals of the SAWfilter 20, and the via hole conductor b17 is connected to the unbalancedterminal of the SAW filter 20. Further, the via hole conductor b17 iselectrically connected to the switch circuit 14 through the wiring andthe like within the multi-layer substrate 12 and the via hole conductorb20. Thereby, as illustrated in FIG. 1, the switch circuit 14 iselectrically connected to the terminals T3 and T4 through the SAW filter20. In other words, the SAW filter 20 is connected between the switchcircuit 14 and the terminals T3 and T4.

The terminals T5 and T6 are connected to the SAW filter 22 respectivelythrough the via hole conductors b5 and b6. Further, the via holeconductors b5 and b6 are connected to the balanced terminals of the SAWfilter 22, and the via hole conductor b21 is connected to the unbalancedterminal of the SAW filter 22. Further, the via hole conductor b21 iselectrically connected to the switch circuit 14 through the wiring andthe like within the multi-layer substrate 12 and the via hole conductorb24. Thereby, as illustrated in FIG. 1, the switch circuit 14 iselectrically connected to the terminals T5 and T6 through the SAW filter22. In other words, the SAW filter 22 is connected between the switchcircuit 14 and the terminals T5 and T6.

The terminals T7 and T8 are connected to the SAW filter 24 respectivelythrough the via hole conductors b7 and b8. Further, the via holeconductors b7 and b8 are connected to the balanced terminals of the SAWfilter 24, and the via hole conductor b25 is connected to the unbalancedterminal of the SAW filter 24. Further, the via hole conductor b25 iselectrically connected to the switch circuit 14 through the wiring andthe like within the multi-layer substrate 12 and the via hole conductorb27. Thereby, as illustrated in FIG. 1, the switch circuit 14 iselectrically connected to the terminals T7 and T8 through the SAW filter24. In other words, the SAW filter 24 is connected between the switchcircuit 14 and the terminals T7 and T8.

The terminals T9 and T10 are connected to the SAW filter 26 respectivelythrough the via hole conductors b9 and b10. Further, the via holeconductors b9 and b10 are connected to the balanced terminals of the SAWfilter 26, and the via hole conductor b25 is connected to the unbalancedterminal of the SAW filter 26. Further, the via hole conductor b25 iselectrically connected to the switch circuit 14 through the wiring andthe like within the multi-layer substrate 12 and the via hole conductorb27. Thereby, as illustrated in FIG. 1, the switch circuit 14 iselectrically connected to the terminals T9 and T10 through the SAWfilter 26. In other words, the SAW filter 26 is connected between theswitch circuit 14 and the terminals T9 and T10.

The terminals T11 and T12 are connected to the SAW filter 28respectively through the via hole conductors b11 and b12. Further, thevia hole conductors b11 and b12 are connected to the balanced terminalsof the SAW filter 28, and the via hole conductor b28 is connected to theunbalanced terminal of the SAW filter 28. Further, the via holeconductor b28 is electrically connected to the switch circuit 14 throughthe wiring and the like within the multi-layer substrate 12 and the viahole conductor b30. Thereby, as illustrated in FIG. 1, the switchcircuit 14 is electrically connected to the terminals T11 and T12through the SAW filter 28. In other words, the SAW filter 28 isconnected between the switch circuit 14 and the terminals T11 and T12.

The terminal T13 is electrically connected to the resistor R1 throughthe via hole conductor b13. The via hole conductor b13 is electricallyconnected to the via hole conductor b31 through the resistor R1. The viahole conductor b31 is electrically connected to the switch circuit 14through the via hole conductor b32. Thereby, as illustrated in FIG. 1,the switch circuit 14 is electrically connected to the terminal T13through the resistor R1.

The terminal T14 is electrically connected to the resistor R2 throughthe via hole conductor b14. The via hole conductor b14 is electricallyconnected to the via hole conductor b33 through the resistor R2. The viahole conductor b33 is electrically connected to the switch circuit 14through the via hole conductor b34. Thereby, as illustrated in FIG. 1,the switch circuit 14 is electrically connected to the terminal T14through the resistor R2.

The terminal T15 is electrically connected to the resistor R3 throughthe via hole conductor b15. The via hole conductor b15 is electricallyconnected to the via hole conductor b35 through the resistor R3. The viahole conductor b35 is electrically connected to the switch circuit 14through the via hole conductor b36. Thereby, as illustrated in FIG. 1,the switch circuit 14 is electrically connected to the terminal T15through the resistor R3.

The terminal T16 is electrically connected to the switch circuit 14through the via hole conductor b16. The terminals T17 to T25 are groundterminals and are each connected to some of the via hole conductorswithout reference symbols illustrated in FIG. 2B.

The terminal T26 is electrically connected to the switch circuit 14through the wiring within the multi-layer substrate 12 and the via holeconductor b39.

A ground electrode covering substantially an entire predetermined layeris provided within the multi-layer substrate 12. Other layers includecoil electrodes and capacitors provided thereon. The coil electrodes andthe capacitors preferably define low pass filters 16 and 18 illustratedin FIG. 1. The multi-layer substrate 12 includes the low pass filters 16and 18 connected between the switch circuit 14 and the terminals T1 andT2. Within the multi-layer substrate 12, the via hole conductors andwiring lines that extend between the switch circuit 14 and the terminalsT13 to T15 define the current paths S1 to S3.

Next, the capacitors C1 to C3 illustrated in FIG. 1 will be described.The capacitors C1 to C3 are preferably provided on the printed circuitsubstrate 50, and first ends thereof are connected to wiring linesconnected to the terminals T13 to T16 and the second ends thereof aregrounded. The first ends of the capacitors C1 to C3 are preferablyconnected to the wiring lines at positions that are farther from theresistors R1 to R3 than the terminals T13 to T16. The capacitors C1 toC3 enable noise that has arisen in the control signals Vc1 to Vc3 topass therethrough to the ground side. Note that the capacitors C1 to C3may be mounted on the multi-layer substrate 12.

In the high-frequency switch module 10 having the configurationdescribed above, the switch circuit 14 connects the terminal T26 to theterminals T3 to T12 corresponding to the frequency bands of thereception signals received by the antenna 30 based on the controlsignals Vc1 to Vc3. Further, the switch circuit 14 connects the terminalT26 to the terminals T1 and T2 corresponding to the frequency bands ofthe transmission signals to be transmitted from the antenna 30 based onthe control signals Vc1 to Vc3. Accordingly, the high-frequency switchmodule 10 can handle the transmission and reception signals in aplurality of types of frequency bands.

In the high-frequency switch module 10 having the configurationdescribed above, noise is prevented from being input to the switchcircuit 14 through the capacitors C1 to C3, as described below. In moredetail, as illustrated in FIGS. 1, 2A, and 2B, the resistors R1 to R3arranged to attenuate the noise passing through the current paths S1 toS3 are preferably respectively provided on the current paths S1 to S3that connect the switch circuit 14 to the terminals T13 to T15. Theresistors R1 to R3 preferably have resistance values greater than thoseof the current paths S1 to S3. Thus, compared to when the noise flowsthrough the current paths S1 to S3 on which the resistors R1 to R3 arenot provided, more noise is converted to thermal energy and the noise issignificantly attenuated when the noise flows through the current pathsS1 to S3 on which the resistors R1 to R3 are provided. The capacitors C1to C3 receive noise that has been attenuated by passing through theresistors R1 to R3. Thus, in the high-frequency switch module 10, theamount of noise input to the switch circuit 14 through the capacitors C1to C3 and a ground electrode (not illustrated) within the printedcircuit substrate 50 is greatly reduced. As a result, in thehigh-frequency switch module 10, the distortion of the harmonics oftransmission signals due to the transmission signals being modulated bynoise is prevented, and the deterioration of the high-frequencycharacteristics of the switch circuit 14 is prevented.

Referring to FIG. 2B, the resistors R1 to R3 are preferably providedalong the side of the switch circuit 14 closest to the connection points(i.e., the via hole conductors b32, b34, and b36) between the switchcircuit 14 and the current paths S1 to S3. Thereby, the distancesbetween the switch circuit 14 and the resistors R1 to R3 is small andnoise is prevented from being input therebetween.

Further, referring to FIG. 2B, the resistors R1 to R3 are preferablyprovided between the switch circuit 14 and the SAW filter 28. The SAWfilter 28 receives the reception signals Rx1 to Rx5 and the switchcircuit 14 receives the transmission signals GSM-Tx1 and GSM-Tx2. Thus,by providing the resistors R1 to R3 between the SAW filter 28 and theswitch circuit 14, isolation between the reception signals Rx1 to Rx5and the transmission signals GSM-Tx1 and GSM-Tx2 is improved.

Further, when static electricity is input to the switch circuit 14through the current paths S1 to S3, the input of the static electricityis effectively controlled by the resistors R1 to R3, thereby preventingthe switch circuit 14 from being damaged by the static electricity.

The inventors of the present invention performed the experimentsdescribed below to further clarify the advantage of the high-frequencyswitch module 10. Specifically, the high-frequency switch module 10provided with the resistors R1 to R3 having a resistance value of about1 kΩ (first exemplary experiment), the high-frequency switch module 10provided with the resistors R1 to R3 having a resistance value of about500Ω (second exemplary experiment), and the high-frequency switch module10 without the resistors R1 to R3 (third exemplary experiment) wereprepared and the signals observed at the RF port were examined. FIG. 3Ais a graph illustrating the results of the first exemplary experiment;FIG. 3B is a graph illustrating the results of the second exemplaryexperiment; and FIG. 3C is a graph illustrating the results of the thirdexemplary experiment. The vertical axis represents the amount of noiseand the horizontal axis represents frequency.

As can be seen from the comparison of FIG. 3A to FIG. 3C, the amount ofnoise is reduced by providing the resistors R1 to R3. Thus, by providingthe resistors R1 to R3, noise is prevented from being input to theswitch circuit 14 through the capacitors C1 to C3. Further, whencomparing FIG. 3A with FIG. 3B, noise is generated, although slightly,in the case of the resistors R1 to R3 having a resistance value of about500Ω, but noise is negligibly generated in the case of the resistors R1to R3 having a resistance value of about 1 kΩ. Accordingly, it ispreferable that the resistors R1 to R3 have a resistance value of atleast about 1 kΩ.

In addition, the inventors of the present application measured theharmonics in the first and third exemplary experiments. The harmonicsare observed in a phenomenon in which, when power is applied to asemiconductor at a certain frequency, power is observed at frequenciescorresponding to the higher harmonic waves of the frequency. The resultsshow that the harmonics in the third exemplary experiment were about −68dBc, whereas the harmonics in the first exemplary experiment were about−85 dBc. In other words, the level of the harmonic signals can bereduced to a greater extent in the first exemplary experiment in whichthe resistors R1 to R3 are provided than in the third exemplaryexperiment in which the resistors R1 to R3 are not provided. This showsthat noise is prevented from penetrating into the switch circuit 14 andthereby modulating the harmonic signals.

Hereinafter, a high-frequency switch apparatus according to anotherpreferred embodiment of the present invention is described withreference to the drawings. FIG. 4 is a block diagram of a high-frequencyswitch apparatus 70′. Hereinafter, a description is provided to describethe differences between the high-frequency switch apparatus 70′ and thehigh-frequency switch apparatus 70 illustrated in FIG. 1.

The high-frequency switch apparatus 70′ is different from thehigh-frequency switch apparatus 70 in terms of the position at which theresistors R1 to R3 provided to reduce noise passing through currentpaths S1′ to S3′ are provided. In the high-frequency switch apparatus70, the resistors R1 to R3 are provided on the multi-layer substrate 12as illustrated in FIG. 1. On the other hand, in the high-frequencyswitch apparatus 70′, the resistors R1 to R3 are preferably provided onthe printed circuit substrate 50 as illustrated in FIG. 4. In moredetail, the current paths S1′ to S3′, first ends of which arerespectively connected to the terminals T13 to T15, are provided on theprinted circuit substrate 50. The resistors R1 to R3 are provided on thecurrent paths S1′ to S3′. In other words, in the high-frequency switchapparatus 70′, the resistors R1 to R3 are preferably provided outside ofa high-frequency switch module 10′. Further, first ends of thecapacitors C1 to C3 are preferably connected to the current paths S1′ toS3′ at positions which are farther from the resistors R1 to R3 than theterminals T13 to T15, and the second ends are grounded. Thisconfiguration prevents noise from being input to the switch circuit 14through the capacitors C1 to C3.

Note that the remainder of the configuration of the high-frequencyswitch apparatus 70′ is substantially the same as that of thehigh-frequency switch apparatus 70, and the description thereof isomitted.

In the high-frequency switch apparatus 70′, the resistors R1 to R3 arepreferably provided in the vicinity of the connection portion of themulti-layer substrate 12 and the printed circuit substrate 50. Thisenables noise generated from the switch circuit 14 to be removed in thevicinity of the switch circuit 14, and the leakage of the noise to otherports of the switch circuit 14 to be significantly reduced.

Further, the printed circuit substrate 50 includes control terminalelectrodes (not illustrated) connected to the second ends of the currentpaths S1′ to S3′. The resistors R1 to R3 may preferably be provided inthe vicinity of the control terminal electrodes. This enables areduction in the leakage of noise from other control terminal electrodesto the control terminal electrodes provided with the resistors R1 to R3.

The high-frequency switch module 10 and the high-frequency switchapparatus 70 are not limited to those described in the preferredembodiments of the present invention, and can be modified within thescope of the present invention. For example, it was assumed that theresistors R1 to R3 are resistor devices and are mounted on themulti-layer substrate 12 or the printed circuit substrate 50. However,resistance portions may be directly provided on the multi-layersubstrate 12 or the printed circuit substrate 50, instead of theresistors R1 to R3. In this case, the resistance portions may be definedby wiring lines made of a material that has a resistance greater thanthat of the current paths S1 to S3, or may be defined by wiring lineshaving widths less than those of the current paths S1 to S3.

Further, although all of the terminals T13 to T15 are provided with therespective resistors R1 to R3 in the high-frequency switch module 10 andthe high-frequency switch apparatus 70, not all of the terminals T13 toT15 need to be provided with the respective resistors R1 to R3. Thereare cases in which there is no influence of noise even when some of theterminals T13 to T15 are not provided with the respective resistors R1to R3. In such a case, some of the terminals T13 to T15 not generatingnoise need not be provided with the respective resistors R1 to R3.

Preferred embodiments of the present invention are useful for ahigh-frequency switch apparatus and a high-frequency switch module, andare particularly advantageous to prevent noise from being input to aswitch circuit through capacitors.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

1. A high-frequency switch apparatus comprising: a first substrate; asecond substrate on which the first substrate is mounted; and a switchcircuit mounted on the first substrate; wherein the first substrateincludes: a common terminal through which a plurality of high-frequencysignals in a plurality of frequency bands are input and output; aplurality of switch terminals; and a control terminal to which a controlsignal to control the switch circuit in accordance with frequency bandof a high-frequency signal input or output through the common terminalis applied; the switch circuit is arranged to connect the commonterminal to the switch terminal based on the control signal; and thesecond substrate includes: a current path including a first end which isconnected to the control terminal; and a resistance portion arranged toreduce noise passing through the current path, the resistance portionbeing provided in series in the current path and having a resistancevalue greater than a resistance value of the current path.
 2. Thehigh-frequency switch apparatus according to claim 1, wherein theresistance portion is provided near a connection portion of the firstsubstrate and the second substrate.
 3. The high-frequency switchapparatus according to claim 1, wherein the second substrate furtherincludes a control terminal electrode including a first end which isconnected to a second end of the current path, and the resistanceportion is connected in the vicinity of the control terminal electrode.4. The high-frequency switch apparatus according to claim 1, wherein thesecond substrate further includes a capacitor including a first endwhich is connected to the current path at a position farther from thecontrol terminal than the resistance portion and a second end which isgrounded.
 5. The high-frequency switch apparatus according to claim 1,wherein the plurality of the switch terminals include a transmittingterminal and a receiving terminal, and the first substrate furtherincludes a low pass filter connected between the transmitting terminaland the switch circuit.
 6. The high-frequency switch apparatus accordingto claim 1, wherein the plurality of the switch terminals include atransmitting terminal and a receiving terminal, and a surface acousticwave filter is connected between the receiving terminal and the switchcircuit.
 7. The high-frequency switch apparatus according to claim 1,wherein the resistance portion has a resistance value greater than orequal to about 1 kΩ.
 8. The high-frequency switch apparatus according toclaim 1, wherein the switch circuit is a semiconductor switch.